We analyze the effects of optical feedback in a laser diode in the frequency of emission and optical output power. We observe experimentally that the dynamics properties of injection laser are affected by the interference between light of the laser diode cavity and backscattered light. We demonstrate that the light intensity shows hysteresis and discrete shifts of frequency according to feedback light and/or forward current variations condition due at non-linear active layer.
We present an alternative development of very cheap sensors utilizing plastic optical fibers and diode lasers extracted from laser pointers. We have applied these sensors to perform measurements of displacement and distance without physical contact. The development of these sensors started with the characterization and control of these semiconductor lasers. We have achieved to control various diode lasers by means of a current controller, specially designed for this application. In this work, we show two different sensor configurations, getting a measurement range between 1 and 3 mm with microns resolution.
This work shows characterization methods for laser pointers as whole system sand also for semiconductor lasers. We started developing a current controller and a power light meter designed and calibrated for this type of work. Characteristic curves as optical power output versus forward current and forward current versus forward voltage and also related characteristic parameters as threshold current are obtained. In addition, far field radiation patterns with their angles of divergence, the astigmatic distance are found. It is intended that these devices can be used for optics and optoelectronics education as well as for the development of measurement and communications systems based in semiconductor lasers.